CYCLOPHORID. 7 
Aperostoma, Pfr. in Zeitschr. f. Mal. 1847, p. 47, 104. 
Cyclostoma (spec.), Gray, Sowerby, ete. 
I, Peristome simple, 
a. Straight ; ‘ : : ee 
5. Expanded : : F ‘ = Sh Ze 26-33 
II. Peristome double 2 igee 
§ 1. Peristome simple, straight. 
1. CycLoTUS GIGANTEUS. B. M. 
Shell rather depressed, solid, with crowded rugose striz ; white, 
with an epidermis of fulvous colour, fading off in bands ; spire 
short, rather acuminate, reddish; whorls 53 convex, rapidly 
increasing, the last one marked with an impressed line near 
the suture, a little deflexed anteriorly, more convex and more 
finely striated beneath ; umbilicus broad; aperture large, 
obliquely ovate, white, shining; peristome straightly blunt, 
the margins angularly joined by a white callus, the right 
margin sinuous. Operculum whitish, of 10-11 whorls. Height 
22 millimeters, greatest breadth 50 mill., least breadth 38 mill. 
Cyclostoma giganteum, Gray, WSS. in Brit. Mus.; Sow. in Proc. 
Zool. Soc. 1843, p. 30; Spec. Conch. f.9, 10; Thes. p. 92, n. 5, 
i 20.4.0, 9 ; heeve, Conch. Syst... t..184, 1.17; Py le: p. Pe 
Wo of lt 14, 
Cyclostoma Cumingii? Jay, Catal. 1839, p. 122, t. 7, f. 4, 5. 
Aperostoma giganteum, Pfr. in Z. f. M. 1847, p. 104. 
Cyclotus giganteus, Gray, Cat. Cycl. p.6; Pfr. Consp.n. 1; Mon. 
Dp. 16; 
Hab. W. Columbia, Salanga ; St. Elena. 
2. CycLoTus QUITENSIS. 
Shell depressed, solid; upper side finely striated, shining, of a 
dark chestnut ; spire short, conoidally elevated ; suture deep ; 
whorls 45, convex, rapidly increasing, the last one depressed 
near the suture, wrinkled, with a narrow whitish girdle and a 
broad blackish band at the periphery, brownish-green beneath, 
with crowded radiating folds round the funnel-shaped umbi- 
licus ; aperture a little oblique, irregularly ovate, expanded to 
the right side, livid; peristome straight, a little thickened, 
continued ; the margins angularly joined above ; the left margin 
shortly appressed on the penult whorl. Operculum typical. 
Height 15 mill., greatest breadth 37, least br. 27 mill. 
Cyclostoma Quitense, Pfr. in Proc. Zool. Soc. 1851; Icon. n. 355, 
t. 44, f. 19-22. 
Cyclotus Quitensis, Pfr. Consp. n. 2, p. 50; Mon. p. 17. 
Hab. Quito. 
